Cobalt magnesia-kieselguhr catalyst



Patented Nov. 3, 195 3 COBALT MAGNESIA-KIESELGUHR CATALYST John W. Teter and Leonard E. Olson, Chicago, 111., assignors to Sinclair Refining Company, New York, N. Y., a corporation of Maine No Drawing. Original application February 11,

1949, Serial No. 75,976. Divided and this application May 20, 1950, Serial No."163,334

3 Claims.

This invention relates to improvements in the production of nitrogen-containing products, particularly nitriles, by the direct catalytic reaction of olefins with ammonia. It includes immovements in the process and particularly comprehends an improved type catalyst which is characterized by high relative activity and catalyst life.

The production of nitrogen-containing products, particularly nitriles, by direct reaction of ammonia with olefins requires relatively high temperatures; e. g. ranging from about 400 F. to about 725 F., elevated pressure; e. g. upwards of 500 p. s. i., and the use of a catalyst which selectively promotes amination in an environment of competing reactions such as hydrogenation, dehydrogenation, cracking, and polymerization. The nature of the catalyst is critical, and cobalt containing catalysts although very costly have been found to be most satisfactory from the standpoint of activity, product distribution, and catalyst life. Our application Serial No. 694,434, filed August 31, 1946, now U. S. Patent No. 2,520,181, describes certain reduced metal oxide catalysts in which a part of the costly cobalt is replaced by another metal which is capable as an oxide of forming a spinel-type crystal structure with cobalt oxide. These catalysts are much more economical than the standard type cobalt catalysts, and have relatively high activities.

We have now discovered that a. catalyst representing the reduction product of mixed cobalt and magnesium oxides supported on a diatomaceous earth carrier possesses peculiarly advantageous properties in selectively promoting the direct reaction of olefins and ammonia. The new type catalyst contains from about 5 to 40 weight per cent of magnesium, up to about 50 weight per cent of cobalt. and upwards of weight per cent of the carrier. catalysts are not in the metallic state, but the probable composition after activation is perhaps a mixture of cobalt, cobalt as cobalt oxide, magnesium oxide and silica.

The new type catalyst may be conveniently prepared, for example, by coprecipitation of the basic carbonates of cobalt and magnesium from a solution of the sulfates of those metals. The precipitant, for example, soda ash, is conveniently applied in solution with which the supporting material, for example, celite, a commercially available diatomaceous earth, is slurried prior to admixture of the hot solutions. We have found that such a catalyst containing. for ex- Actually the ample, 26.5% by weight of cobalt, 23% of magnesium, and 23.9% of celite has a relative activity of 35 weight per cent nitrile yield compared to 28% shown by a standard cobalt on celite catalyst tested under comparable conditions. In

addition, we have found that the useful life of the new catalyst is markedly superior to that of the standard catalyst. For example, in a comparison test in which the standard catalyst and the before-described new catalyst were held for 30 days at the standard processing temperature of 700 F. and were then re-tested for activity, the activity of the standard catalyst declined from an initial activity of 27 to an activity of 18, whereas the new catalyst fell off only slightly, from 35 to 33.

We have found that the molar proportion of cobalt to magnesium, calculated as metal, may vary between approximately 1:2 and 1:8 without serious effect on cobalt eficiency; that is the relationship of yield to weight per cent cobalt. We have found, however, that approximately 10% of celite or a similar diatomaceous type material is necessary for superior activity on both a yield basis and a catalyst life basis. We have found that catalysts containing approximately 25 to 35 weight per cent of cobalt, approximately 5 to 40 weight per cent of magnesium, and say 10 to 25 weight per cent diatomaceous earth are particularly advantageous with respect to catalyst activity and life.

The new catalysts are advantageously prepared in the form of small agglomerates or granules, as by pelleting or extrusion, after deposition of the active ingredients on the inert carrier, and in the process, will advantageously be used in the form of a fixed bed, with the mixture containing the ammonia and olefin being passed through the bed.

The new catalysts are capable of reactivation by hydrogen after having been onstream for a period of time sufficient to cause the catalyst to lose some of its initial activity, and may be used with advantage in the cyclic process described in Teter Patent 2,419,470, issued April 22, 1947, in which two or more reactors are used in parallel, with one reactor onstream while the other is being reactivated by passing hydrogen through it followed by an ammonia purge. However, we have found that the burden of reactivation is considerably reduced because of the improved life of the new type catalyst. In general, in using the new catalyst, it is advantageous to use a large excess of ammonia in the process, as described in Teter Patent 2,417,892, issued March meter, so that .usuallyunnecessary. The

ing the resulting material to convert the metal,

to the oxide or mixture of oxides, and then re-'- ducing the resulting The exact structure of metal mixture is not known. That.is,.it is not known whether in the active catalyst, the'metal is present as such, or whether partofit is present as such, with the remainder present a an oxide, or mixture of oxides, or whether the efiective catalytic material represents some equilibrium. mixture of metal, and one rier in-the form. of thehydroxide or carbonate,

theproduct is washed with demineralized water .to .remove .soluble salts, and in particular, to

In general,

remove sulfate and chloride ions, in the new catalysts, it is desirable to keep the .sulfate content-below, about 0.2%, and the chlo- 0.1%. Sodium, in small ride content below about be an activator .or proquantities, however may product is finallycalcined, pelleted, and reduced. Ordinarily, final reduction will be, carried out in the reactor, although itispossible to reduce the catalyst in another vessel, andthen stabilize it in the known way for transportation. A typical preparation and certain of the principles of our invention willbevillustrated, by the following examples.

Example I A suspension of 540 grams of-.-diatom'ac'eous earth, (Celite #337) is slurried for minutes in 1.5 gallons of a hot (90 C. approximately) solutionof soda ash containing 1270 grams of anhydrous sodium, carbonate (NazCos). One gallon of a hot solution containing 895 grams of cobaltsulfate heptahydrate (00304.71-120). and 13 70 grams of magnesium acetatetetrahydrate (Mg(OAC)z.4H) corresponding to a cobalt to magnesium mole ratio of 1:2 is then added over a half hour period. The slurry is allowed to cool while stirring ior an additional half'hour, and the precipitate filtered off and dried. at 110 ,C.' for 12-16 hours. The driedprecipitate i then broken up and washed with hot water by a series of successive slurrying and filtering procedures until' the sulfate analysis onthe cake drops to 0.10% on an ignited basis. The catalyst cake is then redried at 110 C. ground to pass 20 mesh and calcined for 2 hours at 340 C. Ordinarily, 30, minutes is allowed in addition for the material to. come upto temperature. The calcined material is mixed with 4% graphite and pelleted. The catalyst is thenintroduced into a reactor or more metal oxides. The reduced metal catalyst is pyrophoric,. and;

metal oxide with hydrogen...v

the resulting reducedqo After the the same care in its removal is and reduced as with hydrogen at 3,000 .space velocity and atmospheric pressure for 5 hours,

followed by an ammonia; purge at processing temperature and pressure.

The catalyst so prepared was then used in thev production of nitrogen-containing products monia to olefin in the feed was 10:1. The olefin space ,velocity was 10 volume per volume of catalyst per' hour. The temperature was 700 F., thcpressure 1.500 p. s. i., and the runs were conducted in a cyclic manner over a 1-hour period.v Theyield {of nitrogen-containing productswas 23% '(average of 3 runs) with a product distribution,"relatively high in the desirable propionitrile as follows: acetonitrile 25.2 weight per cent, propionitrile 44.5, isobutyronitrile 4.4, n-butyronitrile 17.9, and water and bottoms 0.8 and 7.2, respectively.

Under comparable test conditions a standard cobalt on celite catalyst containing approximate ly 39% cobalt gave. an average Weightper cent yield over 3 tests of. 28%. Thus the Co:2MgO catalyst containing only 47.5% as much. cobalt gave 82% yield of the standard catalyst. Obviously, this represents a very significantiadvantage from the cost standpoint sincecobalt is by far the mostnexpensive ingredient in these catalysts. From the standpoint of equivalent cobalt content the catalyst of the example had a relative activity of compared to the standard catalyst.

Example II ,alyst 100%, andon the basis of equivalent cobalt content had a relativeactivity. of When testedfor-catalyst life. by holding for 30 days at 700 F., the activity of the catalyst'dropped only to 33 whereas. thestandard catalyst declined from 27. to ,18.

} Further catalyststudies onour new t e lysts establish thatthe activity in terms W Zi g Zt per cent yield of: catalyst increases with increas mg weight'per cent of cobalt up. to an activity of .about.35% to- 40% at .upwards of :25 .toz'about 35 weight percent cobalt, reaching a maximum percentage yield .in .the approximate region of 35%.- These catalysts are all superior to the standard cobalt-celite catalyst in terms of efliciency of cobalt utilization; that is with respect to therelati'onship between yield'and weight per cent cobalt with the superiority most marked over the approximate range of 20' to 50 weight percent cobalt. The activities of the standard cobalt-celite catalyst do not increasequite *as rapidly with 'increasingweightper cent cobalt wit lower. activity values obtained for cash equivalent weight per cent'cobalt and the activity reaches a maximum obtainable value at a lower activities fall of! rapidly as higher concentrations of cobalt are used.

Other examples of useful catalysts that we have prepared are, by way of illustration: 4CozMg on 25% celite which displayed an activity of 31 CozSMg on 15% celite which displayed an activity of 21%, Co:2Mg on 10% celite which displayed an activity of 36 weight per cent nitrile produced. These catalysts are characterized by a high efiicicncy of cobalt utilization combined with long catalyst life. With respect to maximum utilization of reactor volume, however, we consider that catalysts containing approximately 25 to 35 weight per cent cobalt are especially advantageous.

By contrast, a catalyst prepared without a diatomaceous earth support, containing 43.0% cobalt and 26.6 weight per cent magnesium showed an initial activity of only 21.1% despite the high cobalt content. Even more significantly, however, the activity dropped to less than 7% after one test and a standard reactivation in the second hour of testing. Accordingly, we consider that the presence of celite or a similar type support is required for good activity and catalyst life. Typical data on the aforesaid illustrative catalyst preparations and test runs are summarized in the following table:

wt Pep Activity Approximate Catalyst Wt. Per- Wt. Perc'ent Wt. Per- Composition cent cent Mg Came cent Yields 1 Co:2Mg40 celite 18. 5 14. 9 43. 7 23 0o:2Mg-25 celite 26. 5 23. 0 23. 9 35 43. 0 26. 6 none 3 21 48. 1 4. 8 23. 5 31 13. 7 39. l 16. 6 21 33. 4 28.1 8. 3 36 38. 8 none 42.1 28

1 Test Conditions:

700 F.; 1,500 p. s. 1.; 10:l/NH;:0;=mole ratio; 60 minute test 6 1949, now U. S. Patent No. 2,623,061 which in turn. is a continuation in part of our copending application Serial No. 694,434, filed August 31, 1946.

We claim:

1. A catalyst efiective in the production of nitrogen-containing products by the direct reaction of ammonia with olefins and consisting of the reduction product of mixed cobalt and magnesium oxides supported on a diatomaceous earth carrier, in which the molar proportion of cobalt to magnesium is within the approximate range of 1:2 and 1:8, the proportion of cobalt approximates 13.7 to 35 weight per cent, the proportion of magnesium is less than 40 weight per cent and the carrier content is at least about 10 weight per cent.

2. A catalyst effective in the production of nitrogen-containing products by the direct reaction of ammonia with olefins and consisting of the reduction product of mixed cobalt and magnesium oxides supported on a diatomaceous earth carrier, in which the molar proportion of cobalt to magnesium is within the approximate range of 1:2 to 1:8, the proportion of cobalt approximates 20 to 35 weight per cent, the proportion of magnesium is less than 40 weight per cent and the proportion of carrier is at least about 10 weight per cent.

3. A catalyst efiective in the production of nitrogen-containing products by the direct reaction of ammonia with olefins and consisting of the reduction product of mixed cobalt and magnesium oxides supported on a diatomaceous earth carrier, in which the molar proportion of cobalt to magnesium is within the approximate range of 1:2 to 1:8, the proportion of cobalt approximates 25 to 35 weight per cent, the proportion of magnesium is less than 40 weight per cent and the proportion of carrier is at least 10 weight per cent.

JOHN W. TETER. LEONARD E. OLSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,799,452 Beekley Apr. 7, 1931 2,219,042 Heckel et a1 Oct. 22, 1940 2,244,196 Herbert June 3, 1941 2,406,929 Teter Sept. 3, 1946 2,437,051 Sensel et al Mar. 2, 1948 2,445,345 Byrns July 20, 1948 2,468,522 Teter Apr. 26, 1949 2,479,879 Teter Aug. 23, 1949 

1. A CATALYST EFFECTIVE IN THE PRODUCTION OF NITROGEN-CONTAINING PRODUCTS BY THE DIRECT REACTION OF AMMONIA WITH OLEFINS AND CONSISTING OF THE REDUCTION PRODUCT OF MIXED COBALT AND MAGNESIUM OXIDES SUPPORTED ON A DIATOMACEOUS EARTH CARRIER, IN WHICH THE MOLAR PROPORTION OF COBALT TO MAGNESIUM IS WITHIN THE APPROXIMATE RANGE OF 1:2 AND 1:8, THE PROPORTION OF COBALT APPROXIMATES 13:7 TO 35 WEIGHT PER CENT, THE PROPORTION OF MAGNESIUM IS LESS THAN 40 WEIGHT PER CENT AND THE CARRIER CONTENT IS AT LEAST ABOUT 10 WEIGHT PER CENT. 